Conflict resolution/Getting on same page

You have held several meeting with key stakeholders to develop requirements for a major project. Your manger continues to disagree with the team on one of the core requirements. Your manager with significant influence over the project. However, he does not fully understand the underlying technical details/limitations of how to implement the new feature. Despite two deep dive sessions on feature implementation and technical limitations, Your manager continues to claim that his approach is feasible.

Please draft a 2 paragraph email to the project manager outlining the situation and provide recommended next steps.